eastcoastbumps

iTrader: (1)

I'm glad you're having a good laugh, cuz I'm sitting here laughing at you too!

Air has to reach the cap before it can be pushed into the overflow tank. Pressurize it as much as you'd like, but the air will always sit at the highest point. Make the steam pipes the highest point, and only run hoses down, and air will get trapped at the top.

I know exactly how the system works in my swapped car. And its pretty damn good and doesn't have air bubbles. His won't either if he follows my advice.

69LT1Bird

iTrader: (1)

I am not going to bothering arguing, I have worked on enough of these and LT1's so do what you want. I have mine vented to a heater hose just like I did with the Lt1 I used to have and I get no air. The air from the heads as no place else to go but out the vent tube and the air will go to where ever you send it. High or low it really doesn't matter. As long as it leaves the heads and goes back into the main system get burped out of the system.

Here is a good thread with some very respected builders. It even shows production vehicles with the vent set up to a heater hose.
https://ls1tech.com/forums/showthrea...=658765&page=2

eastcoastbumps

iTrader: (1)

Thanks for the link. I guess it can work that way.

Also make note of this post: https://ls1tech.com/forums/showpost....9&postcount=16

The GM LS1 swap manual suggests you vent it to a higher point, not lower.

Kamin

DO NOT PLUG THE LINES.

you can trap air in the heads and cause serious problem that you will never see because you dont monitor the coolant temps inside the heads.

i ran mine to the heater hoses and its worked fine.

Pop N Wood

iTrader: (1)

There are two schools of thought here. One that speculates they must be there for a reason, and guys who have actually plugged them and not had any problems.

The early LS motors use to vent all 4 corners. Some where along the line they deleted the vents fromt the rear of the car. Guess even GM realized they weren't needed back there.

Quite a few guys have plugged them and not seen problems. Some claimed to personnally know GM engineers who say the vents are only needed to cool the throttle body.

Who you gonna believe?

SMAX

iTrader: (11)

Actually it wasn't used to cool the throttle body, but actually to heat it. Personally I think it is just good insurance to avoid hot spots in the heads. Just my $.02 though.

Kelly.

the steam vent tube does not have to be at the highest part of the system,
here is a picture of an envoy engine:


it is CLEARLY lower then the heads, so unless GM designed their own system wrong, i think it will be ok.

here is what i did:




i need a longer vent hose and a different overflow hose and i can fill/burp/test the system.

pist0lpete

iTrader: (3)

The only thing I don't really like about that method is if your thermostat ever goes bad you will have to redo it all over again unless you used one of the newer thermostat housings that you can just replace the thermostat on.

Kelly.

the thermostat is cheaper then the water pump

Rodder

iTrader: (2)

In a static system, the air bubble is going to get trapped at the highest point in the system. When you add flow into the equation, then the air bubble may or may not travel with the flow, depending the fliud dynamics around the location of the air bubble. The steam vents add an additional flow path right through where an air bubble would sit, so that the flow can suck it to another part of the system, hopefully the radiator where it will get trapped at the top and out of the coolant flow.

98Camarod

iTrader: (43)

Question for everyone here. I stood up the radiator and have only one port now. Would using a T with the overflow be wrong? Would that pressurize the overflow tank?

poconojoe

iTrader: (43)

Maybe you should pull the valve cover and see if there is any water jacket located above the ruler. I not going to agrue, but yes you need them and the hose has to go up. It doesn't mater that the system is under pressure, so is the air or steam, so it will stay at the top. Rather then do what you did, you'd have been better off putting petcocks and bleeding the air off. You could always get an air sperator, sort of like steam radiators have and bleed it off to the overflow tank.

rsz288

The steam hole into the water jacket is at the highest point that any gas would rise to inside the water jacket.

The vents, as another poster or two pointed out, are there to ensure no air pockets prevent the coolant doing its coolant thing, which absorbs heat much better than gas/air.

The primary function is to bleed off any air during/after the first fill of coolant which may also create an "air lock" with a large bubble of air which prevents a lot of coolant from getting into place, and to ensure no hotspots arise from air locks from subsequent fills or the odd bubble of air.

The initial fill scenario needs the vent pipes to vent upwards as far as possible to get any air to the top of the radiator where it can do the least damage, and simply vent out through the open cap and achieve maximum coolant fill.

It is there for insurance against the scenario of an air lock occuring.

While heated throttle bodies were common place in the carb days, to improve cold start and reduce HC emissions, any use of heat on a dry air TB these days is most likely to assist in quicker de-icing. GM did away with this before long anyway.

FWIW Cheers.

Project GatTagO

iTrader: (7)

The vent tube needs to go after the thermostat.

Andrew

bgblockelcamino

iTrader: (9)

think the TBSS has a fitting in one of hte heater hoses. i made a t fitting in my heater hose and have not had probs with it yet. and my heater hoses are looped at the water pump as i do not have heat either.

miro

iTrader: (3)

The system is pressurized to increase the boiling point of the coolant. I don't think the pressure would help force air bubbles out of the system. The flow of the coolant is what gets the air bubbles moving and hopefully to the rad. The bubbles would still probably get out of the heads if the steam vent was at a lower point, but it would be a lot easier for the bubbles to get out if the vent was higher than the heads.

OP, maybe you should look into a "coolant breather tank." It makes for a more efficient cooling system and gives you a place to route the steam vent hose to. Check out the diagram at the bottom of this page: http://www.gtfactory.jp/cms/page.php?11

69 Ghost

Guys too much thinking here. Anybody consider that air compresses under pressure? Sorry but it does not have to be the highest point back into the system to purge. Here is my solution. If you do a search for Motormite or Dorman tees you will find a plastic tee fitting you can get either a 5/8" or 3/4" with the tee as 3/8". Part number 47112 you can find them in the help section at any of your favorite local parts stores. Tie that into the heater hose and you are done.


http://www.midwayautosupply.com/pc-1...-34-47112.aspx

RICE ETR

iTrader: (3)

Into the T stat housing is a good idea...wish I would have done that. Eitherway here is what I did since I am not running the powersteering heater lines.

3800RS

iTrader: (15)

can this be done ??

98Camarod

iTrader: (43)

No, it would pressurize the overflow tank